Use of solvent-, water- and emulsifier-free organo-polysiloxane formulations as lubricants for profiled seals

ABSTRACT

The invention provides for, inter alia, the use of solvent-, water- and emulsifier-free preparations for the friction-reducing coating of rubber profiles, comprising  
     (a) about 0.5 to about 35, preferably about 2 to about 5, parts by weight of a curable siloxane and  
     (b) about 65 to about 99.5, preferably about 95 to about 98, parts by weight of low molecular weight volatile silicone oils and, if appropriate,  
     (c) customary auxiliaries and additives.

RELATED APPLICATIONS

[0001] This application claims priority to European application 002008603.9, filed Apr. 17, 2002, herein incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to the use of solvent-, water- and emulsifier-free preparations for the friction-reducing coating of rubber profiles, comprising a curable siloxane and, as a carrier, low molecular weight volatile siloxanes.

[0004] 2. Description of the Related Art

[0005] Waterproof or moistureproof and/or fast air and/or gas exchange-preventing seals are needed for a large number of applications, in particular in the construction sector for the sealing of windows and doors. Profiled seals of this type are of very varied design with respect to shape and material, in particular in the functional sealing field.

[0006] It is common to all profile seals that they are attached using one of the known fixing techniques to the support on which the intended sealing action is to be produced.

[0007] One of the most frequently used fixing techniques consists in pressing prefabricated profiled seals into the corresponding profiles of supports intended therefor, such as, for example, window frames and door frames.

[0008] In order to make possible installation which is as friction-less and energy-saving as possible, the profiled seals are customarily coated on the surfaces with friction-reducing coatings.

[0009] In the processes described in U.S. Pat. No. 4,572,875 and U.S. Pat. No. 4,572,871, silicones or fluorinated resins are added to the lubricant. Coatings of this type firstly have the disadvantage that the silicones are oils, of which it is known that they act as releasing agents. On account of their characteristic substance properties, releasing agents of this type are relatively easily removed and can, for example, lead to difficulties during the installation and in the subsequent coating of frames, vehicle body parts etc. The employment and use of silicone oils which are not firmly bound is therefore not desirable.

[0010] According to U.S. Pat. No. 6,057,042, solvent-containing at least two-component silicone formulations which evaporate the solvent and crosslink at room temperature within 24 hours are applied to the elastomers. The resulting curable layer should be non-tacky and water-repellent, have good adhesion to, in particular, EPDM surfaces, and on account of their good lubricant action the coated elastomers are also proposed for seals in the construction field. These solid films, however, do not achieve the friction-reducing action of the liquid, silicone oil-containing formulations.

OBJECTS OF THE INVENTION

[0011] It was therefore an object of the invention to make available lubricant formulations for profiled seals which fulfill the requirements with respect to lubricant action, but later, after installation of the windows and doors, form a solid film which can no longer be removed and washed off on account of weathering effects and thus also at the same time forms a permanent protection from moisture and improves the tightness of the profile.

SUMMARY OF THE INVENTION

[0012] This object and others were achieved by use of solvent-, water- and emulsifier-free preparations for the friction-reducing coating of rubber profiles, comprising a curable siloxane and, as a carrier, low molecular weight volatile siloxanes.

DESCRIPTION OF THE INVENTION

[0013] One embodiment of the invention is the use of solvent-, water- and emulsifier-free preparations for the friction-reducing coating of rubber profiles, comprising:

[0014] a) about 0.5 to about 35, preferably about 2 to about 5, parts by weight of a siloxane which is curable, optionally in the presence of a catalyst, and

[0015] b) about 65 to about 99.5, preferably about 95 to about 98, parts by weight of low molecular weight volatile silicone oils of the general formula (I) and/or cyclic compounds of the general formula (Ia)

[0016] where

[0017] n is a number from 2 to 10, for the linear compounds and for the cyclic compounds preferably >4, and, if appropriate,

[0018] (c) customary auxiliaries and additives.

[0019] As customary auxiliaries and additives, the compositions according to the invention can contain soluble dyes, colored pigments, delustering agents and other customary auxiliaries. Preferred delustering agents are those based on silicic acid, a particularly preferred black colored pigment is carbon black. The preparations according to the invention are utilizable for the customarily used materials of the sealing profiles such as elastomers made of natural or synthetic materials such as rubber, EPDM.

[0020] The application to the substrates is carried out by the customary processes such as rolling, spreading with a doctor blade and in particular immersing or spraying.

[0021] The curable siloxanes (a) which can additionally be used according to the invention and the various curing conditions are described in the literature, in particular also in Walter Noll, “Chemie and Technologie der Silikone” [Chemistry and Technology of the Silicones], Verlag Chemie GmbH, Weinheim, 1960.

[0022] In addition, cured siloxane products also result from the addition reaction of α,ω-vinylsiloxanes and hydrogensiloxanes. The catalyst used here is, for example, hexachloroplatinic acid.

[0023] Inter alia, RTV (room temperature vulcanizable) rubber systems are also suitable. Constituents of such systems are, for example, alpha,omega-siloxanediols of medium viscosity and, as crosslinkers, for example, methyltriacetoxysilane and also ethoxysilanes. These systems can cure using condensation catalysts, such as, for example, dibutyltin dilaurate, to give a migration-stable film.

[0024] For the production of RTV-crosslinked systems, alkoxypolysiloxanes and silica esters are also used, which then likewise form cured and elastic films with alpha,omega-siloxanediols. Here too, dibutyltin dilaurate is used as a condensation catalyst.

[0025] The silicic acid esters which can additionally be used as crosslinkers are compounds of the general formula

(R²O)_(c)SiO_((4−c)/2),

[0026] in which

[0027] R² is an alkyl radical, preferably C₁₋₄ radical, most preferably an ethyl radical and

[0028] c has a value from 1.8 to 4. If the silicic acid ester is present in monomer form, c has the value 4 and falls with increasing degree of polymerization to values smaller than 4.

[0029] The silicic acid esters additionally used according to the invention preferably have a value of c=2.1 to 4.0.

[0030] As carrier (b), low molecular weight silicone oils are used, which firstly assist the lubricant action of the film which is still present in liquid form, but also evaporate later on account of their high volatility.

[0031] These are linear compounds of the general formula (I) and/or cyclic compounds of the general formula (Ia) such as decamethylpentacyclosiloxane

[0032] where

[0033] n is a number from 2 to 10, for the linear compounds preferably 2 to 5 and for the cyclic compounds preferably >4, particularly 5 and/or 6.

[0034] Cyclic and linear siloxanes can be used on their own or as a mixture with one another, but preferably as a mixture with one another.

[0035] For practical application it is important that the lubricant formulation has a flashpoint of > about 55° C., whereby the content of very low molecular weight siloxanes is thus limited.

[0036] The lubricant formulation according to a+b according to the invention and, if appropriate, c can be applied in the immersion or spraying process. In order to achieve an extremely thin film, a spray application using extremely fine nozzles is preferred. On account of the excellent flowability and crosslinkability of the low molecular weight siloxanes, a homogeneous and extremely thin lubricant film results. This firstly remains liquid up to the processing of the coated rubber profile, so that the drawing and sliding into window and door frames is possible without problems. As a rule, the continuously manufactured coated rubber profile is rolled up and packed in plastic films. Using this measure prevents the easily volatile carrier from being able to evaporate prematurely and a not yet desirable curing of the film taking place.

[0037] After the installation of the windows and doors which contain the coated rubber profiles, the silicone film dries so that a grip-resistant migration-stable film remains. This film imparts a silky lustrous finish to the rubber profile, at the same time serves as weather protection and can thus also improve the sealing ability of the entire profile.

[0038] Use examples:

EXAMPLE 1

[0039] As the curable siloxane (a):

[0040] 3 parts by weight of an alpha,omega-vinylsiloxane (0.28 mmol of vinyl/g)

[0041] 0.15 parts by weight of a methylhydrogenpolysiloxane (10 mmol of SiH/g)

[0042] 0,002% of hexachloroplatinic(IV) acid 6-hydrate were dissolved in a carrier (b) consisting of:

[0043] 20% of dimethylpolysiloxane of the general formula (I) having an average value of n=4 and

[0044] 76% of decamethylpentacyclosiloxane. For a coating experiment, an EPDM profile manufactured in endless form was used.

[0045] The preparation according to the invention was uniformly coated in a spraying chamber through which the EPDM strip was drawn at a rate of 20 m/min. The coated EPDM profile was then wound onto a spool. This spool was packed in a polyethylene film and heat-sealed. At a later point in time, this coated rubber profile was drawn into a wooden window frame. A very good lubricant action was discernible. This installed rubber profile was assessed with respect to its film condition after 14 days. The silicone coating showed a grip-resistant and dry condition. Liquid silicone was no longer discernible.

EXAMPLE 2

[0046] As the curable siloxane (a):

[0047] 1.5 parts by weight of α,ω-methylsiloxanediol having a molecular weight of 6,500

[0048] 3.0 parts by weight of an alkoxy-functional polysiloxane of the formula (CH₃)_(1.5)(C₂H₅O)_(0.75)SiO_(0.88)

[0049] 0.5 parts by weight of a silica ester of the formula (C₂H₅O)_(2.4)SiO_(0.8)

[0050] 0.1% of dibutyltin dilaurate were dissolved in a carrier (b) with:

[0051] 20% of a dimethylpolysiloxane of the formula (I) having an average value of n=3.5 and 75% of decamethyl-pentacyclosiloxane.

[0052] Using this preparation according to the invention, a coating experiment was carried out in an analogous manner to Example 1. On inserting the coated profile a liquid film was likewise discernible, so that very easy insertion of the profile into the window and door frames was discernible.

[0053] After 14 days, a sensory examination of the coated rubber profile was carried out. A dry and migration-stable film was discernible.

COMPARISON EXAMPLE

[0054] In an analogous manner to Example 1, a coating experiment was carried out using a silicone oil emulsion. The silicone oil emulsion from the prior art contains 35% of a dimethylpolysiloxane of viscosity 350 cP and 5% of a non-ionic emulsifier. The profiles coated in an analogous manner had to be blown off with compressed air after coating in order to guarantee a uniform distribution.

[0055] The coated EPDM strip was then rolled onto a spool and packed in a plastic film and heat-sealed in the same manner. On inserting this strip into window and door frames a very greasy silicone film present in liquid form was discernible, which showed a good lubricant action and made possible insertion into the window frames.

[0056] After 14 days, a sensory examination of the coated profile was performed. A greasy film was seen. This film naturally contains the components of the emulsifier used. Traces of silicone were already discernible on the window frames, so that after coating craters also appeared.

[0057] The examples given here confirm the excellent action of the preparations according to the invention and their problem-free use. For the user, the advantage results that water- and emulsifier-free preparations are used which have excellent flow properties and no longer make necessary a later after treatment with compressed air with the further advantage that a migration-stable film is now present which is not able to cause any coating defects. The use of these lubricating and coating agents can thus considerably improve the prior art.

[0058] The above description of the invention is intended to the illustrative and not limiting. Various changes or modifications in the embodiments described herein may occur to those skilled in the art. These changes can be made without departing from the scope or spirit of the invention. 

1. A friction-reducing coating for a rubber profile that does not conain a solvent, water or an emulsifier which comprises: (a) about 0.5 to about 35, parts by weight, based upon the total amount of components (a) and (b), of a curable siloxane and (b) about 65 to about 99.5, parts by weight based upon the total amount of components (a) and (b), of at least one low molecular weight volatile silicone oil of formula (I) and/or a cyclic compound of formula (Ia)

where (c) optionally auxiliaries or additives.
 2. A friction-reducing coating according to claim 1, which comprises about 2 to 5 parts by weight, based on the total amount of components (a) and (b), of at least one curable siloxane and about 95 to 98 parts by weight, based on the total amount of components (a) and (b), of at least one low molecular weight volatile silicone oil of formula (I) and/or at least one cyclic compound of formula (Ia).
 3. The friction-free coating according to claim 1 which further comprises a curing catalyst.
 4. The friction-free coating according to claim 3 wherein the catalyst is hexachloroplatinic (IV) acid 6-hydrate or dibutyltin dilaurate.
 5. The friction-free reducing coating according to claim 1 wherein the low molecular weight volatile silicone oil is a dimethylpolysiloxane of the formula


6. The friction-free coating according to claim 1 wherein the low molecular weight volatile silicone oil is a cyclic polysiloxane of the formula


7. The friction-free coating according to claim 1 which comprises. (a) 0.5 to 35, parts by weight, based upon the total amounts of (a) and (b), of a curable siloxane and (b) 65 to 99.5, parts by weight, based upon the total amounts of (a) and (b), of low molecular weight volatile silicone oils of the formula (I) and/or a cyclic compound of the formula (Ia)

(c) optionally auxiliaries and additives.
 8. The friction-free coating according to claim 1, wherein the volatile low molecular weight silicone oil is decamethylpentacyclosiloxane.
 9. The friction-free coating composition which comprises a mixture of linear and cyclic silicone oils.
 10. The friction-reducing coating according to claim 1 wherein the volatile low molecular weight silicone oil has a flash point of greater than 55° C.
 11. The friction-reducing coating according to claim 1 which further comprises a cross linker to the formula. (R²O)_(c)SiO_((4−c)/2), where R² is an alkyl radical and c has a value from 1.8 to
 4. 12. The friction coating composition according to claim 1, wherein a cyclic compound of formula (Ia) is rpesent and n is a number from 4 to
 10. 13. A profile seal which is coated with the friction-reducing coating according to claim
 1. 14. A support which comprise the profile seal according to claim
 12. 15. The support according to claim 13 which is a door or window-frame.
 16. A method for lubricating a rubber profile which comprises applying a friction-free coating according to claim
 1. 